Den 27.01.2022 20.59, skrev Sam Ravnborg: > Hi Noralf, > > On Tue, Jan 25, 2022 at 06:57:00PM +0100, Noralf Trønnes wrote: >> Add a driver that will work with most MIPI DBI compatible SPI panels. >> This avoids adding a driver for every new MIPI DBI compatible controller >> that is to be used by Linux. The 'compatible' Device Tree property with >> a '.bin' suffix will be used to load a firmware file that contains the >> controller configuration. > > Loading a configuration from a firmware file is very > elegant - I like. > This will be very useful in a million cases with a lot of small panels! > Yes I really hope we can find a way to get this accepted. >> + >> + /* >> + * Optional MIPI commands to execute when the display pipeline is enabled. >> + * This can be used to configure the display controller. >> + * >> + * The commands are stored in a byte array with the format: >> + * command, num_parameters, [ parameter, ...], command, ... >> + * >> + * Some commands require a pause before the next command can be received. >> + * Inserting a delay in the command sequence is done by using the NOP command with one >> + * parameter: delay in miliseconds (the No Operation command is part of the MIPI Display >> + * Command Set where it has no parameters). >> + * >> + * Example: >> + * command 0x11 >> + * sleep 120ms >> + * command 0xb1 parameters 0x01, 0x2c, 0x2d >> + * command 0x29 >> + * >> + * Byte sequence: >> + * 0x11 0x00 >> + * 0x00 0x01 0x78 >> + * 0xb1 0x03 0x01 0x2c 0x2d >> + * 0x29 0x00 >> + */ > Using a binary file that is unreadable when it is first created is less > elegant. > I am sure you have considered a txt file - and I know parsing a txt file > in prone for more errros than parsing a binary file. > > > But if the text file looked like: > " > # The is a comment > cmd 0x11 0x00 > > # We need to sleep > sleepms 120 > > # Do something more > cmd 0xb1 0x03 0x01 0x2c 0x2d > cmd 0x29 0x00 > " > > The file is easier to comment (document) and easier to read and > modify. > The suffix could be ".panel" to tell this is something specific for > a panel. > Using lib/parser could make the code somewhat simple but I did not try > to code it myself. > > The code you included below for the binary file is very simple, > but you shift the burden to the people who have to create binary files. > And people using obscure displays are not always so good at this stuff. > Parsing text files in the kernel sounds very scary, not something that I would like to try. I will make a script that generates and parses the binary representation (which is big endian so it's somewhat readable with xxd or the like). There's a wiki link in the MAINTAINERS entry that will have info about the format including the script. It will also serve as a place to share config snippets/script incantations for displays. I will make the script when the file format is decided upon. Here's the hack I currently use: https://gist.github.com/notro/3ca61c48e7dcc4a0ef34dbadbc30bfa5 Noralf.
